JPH10131953A - Double end support pivoted thrust bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rotational stability of a rotary shaft by preventing eccentricity between a center axis of a ball and a center axis of the rotary shaft. SOLUTION: This device is constituted by a sleeve 20 respectively mounted in a pair of bearing brackets 10, rotary shaft 30 inserted to a through hole 25 in each sleeve 20 to be formed with a dynamic pressure generating groove 30a in a peripheral surface opposed to an internal peripheral surface of each through hole 25, pair of thrust supports 40 respectively mounted in the other side of a pair of bearing brackets 10, ball 35 inserted between both ends of the rotary shaft 30 and a pair of the thrust supports 40, and a position fixing means 32 coming into contact with the ball 35 to be formed in both ends of the rotary shaft 30 in order to prevent right/left movement of the ball 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pivot thrust bearing device which supports both ends, and more specifically, a steel ball (ball) inserted at the center of the rotation shaft to reduce frictional resistance between the rotation shaft and the thrust support. The present invention relates to a both-end supporting pivot thrust bearing device in which ball grooves are formed at both ends of a rotating shaft so as to exactly match each other.

[0002]

2. Description of the Related Art In recent years, drive motors requiring various devices due to the continuous development of the information and computer industries, such as a polygon mirror drive device of a laser printer, a spindle motor of a hard disk, a head drive motor of a VCR, etc.
Due to the characteristics of the equipment, high precision and ultra-high-speed rotation performance with no shaft oscillation vibration are required, and the rotation of the drive motor shaft is linked to the deterioration of the equipment immediately, so that it rotates stably at high speed. Along with the development of the drive motor, various kinds of bearing devices for rotating the rotation shaft of the drive motor precisely and at ultra-high speed have been used.

[0003] As such a bearing device, a dynamic pressure type in which a predetermined fluid flows into a friction boundary surface which is rubbed with a rotating shaft to form a fluid boundary layer by a generated fluid pressure to reduce friction with the rotating shaft. A fluid bearing device, a both-end supporting pivot thrust bearing for supporting a thrust load by balls inserted at both ends of a rotating shaft, and the like are used.

The present invention relates to a double-sided pivot thrust bearing device among various conventional bearing devices as described above. FIG. 3 is a partial sectional view of a conventional double-sided supporting pivot thrust bearing device. As shown in the drawing, a conventional double-sided supporting pivot thrust bearing device includes a rotating shaft 30 having a dynamic pressure generating groove 30a formed on an outer peripheral surface thereof, and a sleeve 20 in which the rotating shaft 30 is inserted into a through hole 25 formed therein. And a thrust support 40 that supports a thrust load with balls 35 interposed at both ends of the rotating shaft 30. The reference numeral 10 indicates a lower bearing bracket. Although FIG. 3 shows only a part of the both-end supporting pivot thrust bearing device, in an actual application, the structure of FIG. 3 has a vertically symmetrical form, and the upper structure is omitted here for convenience of explanation. did.

[0005]

With the above structure,
In order to rotate the sleeve and the rotating shaft in a non-contact manner, the diameter of the rotating shaft is smaller than the inner diameter of the sleeve, and usually a predetermined space is formed. However, when the rotating shaft does not rotate, the rotating shaft is not located at the center of the sleeve, and in most cases is eccentric from the center of the sleeve by ΔL in a predetermined direction as shown in FIG. I have. At this time, since the ball is fixed between the thrust support and the end of the rotating shaft, the load support point is located at the center of the ball at the initial stage when the rotating shaft starts rotating in accordance with the eccentric distance between the rotating shaft and the ball. No longer. Therefore, when the rotation starts or stops, there is a problem that the rotation shaft comes into contact with the sleeve and rotation stability is reduced.

Accordingly, the present invention has been devised to solve the above-mentioned problems, and its object is to make the center of the rotation axis relative to the center of the ball even when the rotation axis is stopped. An object of the present invention is to provide a both-end supporting pivot thrust bearing device in which the rotating shaft can be stably rotated without being eccentric to the side.

[0007]

According to a feature of the present invention to achieve the above object, sleeves respectively mounted on a pair of bearing brackets, and sleeves inserted into the through holes in each of the sleeves. A rotating shaft having a dynamic pressure generating groove formed on the outer peripheral surface facing the inner peripheral surface, a pair of thrust supports mounted on the other side of the pair of bearing brackets, and both ends of the rotating shaft and the pair of thrust supports, respectively. A double-ended pivot thrust bearing device including a ball inserted therebetween and position fixing means formed at both ends of a rotating shaft to contact the ball and prevent the ball from moving left and right is disclosed.

[0008] Preferably, the position fixing means includes a groove having a central axis coinciding with the central axis of the rotation axis, and more preferably, the cross-sectional shape of the groove includes a triangular shape, an arc shape, or a trapezoidal shape. One of the vertexes of the groove having a triangular cross section is located on the center axis of the rotation axis, and the ball contacts the inner wall of the groove.

[0009] The curvature of the arc of the groove having a circular cross section is the same as or larger than the curvature of the ball.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. However, the same components as those of the related art are given the same numbers.
FIG. 1 is a sectional view showing a polygon mirror driving apparatus of a laser printer using a pivot thrust bearing supported at both ends according to the present invention.

As shown, sleeves 20 having through holes 25 formed therein are inserted into one side of the upper and lower bearing brackets 10 and fastened and fixed to the upper and lower bearing brackets 10 by fixing screws and the like, and thrusts are provided on the other side. Each support 40 is inserted and secured to the upper / lower sleeve 20 with screws. A rotating shaft 30 is provided in the through hole 25 in the sleeve 20.
Is inserted, and a herringbone-shaped dynamic pressure generating groove 30a is formed on the outer peripheral surface of the rotating shaft 30 inserted into the through hole 25 in the sleeve 20 so that the sleeve 20 and the rotating shaft 30 can rotate without contact. . A large number of the dynamic pressure generating grooves 30a are formed at regular intervals, the angle β formed by the dynamic pressure generating grooves 30a is generally 30 °, and the depth and area of the dynamic pressure generating grooves 30a are Is determined by its own weight and load.

A polygon mirror 80 for reflecting a laser beam on a photosensitive drum of a laser printer is press-fitted and fixed to the rotating shaft 30, and a plate 60 of which only a part is shown is fixed to the rotating shaft 30 by a hub 70. I have. According to an embodiment of the present invention, a conical ball groove 32 is formed at both ends of the rotating shaft 30 inserted into the through hole 25 in the sleeve 20, and the vertex of the conical ball groove 32 is Located on the central axis. The ball 35 is inserted between the conical ball groove 32 and the thrust support 40, and the ball 35 comes into line contact with the inner wall 32 a of the conical ball groove 32 when stopped. Such line contact can prevent the rotation shaft 30 from moving left and right.

Hereinafter, the operation of the both-end supporting pivot thrust bearing device according to an embodiment of the present invention will be described using a polygon mirror driven scanner motor of a laser printer as an example. First, after inserting and fixing the sleeve 20 on one side of the upper bearing bracket 10 and inserting and fixing the upper thrust support 40 on the other side, the sleeve 20 is also inserted and fixed on one side of the lower bearing bracket 10, The lower thrust support 40 is inserted and fixed.

Next, the balls 35 are inserted into the sleeves 20, respectively, and the rotary shafts 30 having the conical ball grooves 32 formed at both ends of the sleeves 20 are inserted. At this time, the hub 70 in which the polygon mirror 80 and the plate 60 are coupled to the rotating shaft 30 is already press-fitted and fixed. Finally, the upper and lower bearing brackets 10 and 10 are connected and fixed to complete the scanner motor.

When power is applied after the scanner motor has been assembled as described above, the rotation of the plate 60 causes the rotation shaft 30 and the polygon mirror 80 fixed thereto to rotate. At this time, fluid flows into the A and C portions of the dynamic pressure generating groove 30a, and in the B portion, the fluid flowing into the A and C portions is collected to form a predetermined fluid pressure.
Is rotated away from the sleeve 20 without contact.

According to the present invention, when the rotation shaft 30 starts rotating, the center axis of the ball 35 and the center axis of the rotation shaft 30 exactly match. That is, the ball 35 is accurately divided into two by the apexes of the conical ball grooves 32 formed at both ends of the rotating shaft 35, and the apex of the ball groove 32 and the central axis of the ball 35 coincide. At this time, since the vertex of the ball groove 32 is located at the center axis of the rotation shaft 30, the ball 3
The center axis 5 and the center axis of the rotating shaft 30 are always located in the same state.

Therefore, even when the rotation is started, the center is aligned, that is, the center of the rotation axis rotates without being eccentric to any side with respect to the center of the ball.
The rotating shaft can rotate stably. Also, at the time of stopping, the rotation speed is close to 0 and the center of the rotation axis is not eccentric with respect to the center of the ball by the ball groove, so that the rotation can be stopped stably without friction with the inner wall of the through hole of the sleeve. There is an advantage that rotation safety can be ensured.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art to which the present invention pertains can make various modifications without departing from the spirit and spirit of the present invention. it can. For example, as shown in FIG. 2A, a ball groove having a hemispherical cross section having a predetermined curvature is formed, or as shown in FIG. A ball groove having a trapezoidal cross-sectional shape can be formed as much as possible.

[0019]

As described above, according to the present invention, ball grooves are formed at both ends of the rotating shaft to make the balls adhere to each other to prevent eccentricity between the center axis of the ball and the center axis of the rotating shaft. This has the effect of increasing the rotational stability of the rotating shaft.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a polygon mirror driving device of a laser printer using a pivot thrust bearing supported at both ends according to the present invention.

FIG. 2 is a modification of another ball groove shape according to the present invention.

FIG. 3 is a partial cross-sectional view of a conventional both-end supporting pivot thrust bearing device.

DESCRIPTION OF SYMBOLS 10 Upper and lower bearing bracket 20 Sleeve 25 Through hole 30 Rotating shaft 30a Dynamic pressure generating groove 32 Conical ball groove 32a Inner side wall 35 Ball 40 Thrust support 60 Plate 70 Hub 80 Polyhedral mirror

Claims (8)

[Claims] 1. A pair of sleeves respectively mounted on one side of a pair of bearing brackets; and a dynamic pressure applied to an outer peripheral surface of each of the sleeves, which is inserted into a through hole in each of the sleeves and faces an inner peripheral surface of each of the through holes. A rotating shaft having a generating groove formed thereon, a pair of thrust supports respectively mounted on the other side of the pair of bearing brackets, and a ball inserted between both ends of the rotating shaft and the pair of thrust supports; And a position fixing means formed at both ends of the rotating shaft to prevent the ball from moving left and right by contacting the ball. 2. The both-end supporting pivot thrust bearing device according to claim 1, wherein the position fixing means includes a groove having a central axis coinciding with the central axis of the rotating shaft. 3. The bearing according to claim 2, wherein the groove has a triangular cross section. 4. The groove according to claim 3, wherein one of the vertices of the groove is located on a center axis of the rotation axis, and the ball contacts an inner wall of the groove. Both ends support pivot thrust bearing device. 5. The double-sided supporting pivot thrust bearing device according to claim 2, wherein a cross-sectional shape of the groove includes an arc shape. 6. The double-support pivot thrust bearing device according to claim 5, wherein the curvature of the arc is equal to or greater than the curvature of the ball. 7. The both-end supporting pivot thrust bearing device according to claim 2, wherein a cross-sectional shape of the groove includes a trapezoidal shape. 8. The pivoted thrust bearing device according to claim 7, wherein the ball contacts an inner wall of the trapezoid.